Class II Division 1 malocclusion treatment with extraction of maxillary first molars: Evaluation of treatment and post-treatment changes by the PAR Index.

Johan W Booij,Mette A.R Kuijpers,Yijin Ren,Anne Marie Kuijpers‐Jagtman,Christos Livas,Ewald M Bronkhorst,Christos Katsaros

doi:10.1111/ocr.12412

Abstract

ObjectiveTo investigate occlusal result and post‐treatment changes after orthodontic extraction of maxillary first permanent molars in patients with a Class II division 1 malocclusion.Setting and SampleRetrospective longitudinal study in a private practice, with outcome evaluation by an independent academic hospital. Ninety‐six patients (53 males, 43 females) consecutively treated by one orthodontist with maxillary first permanent molar extraction were studied, divided into three facial types, based on pre‐treatment cephalometric values: hypodivergent (n = 18), normodivergent (n = 21) and hyperdivergent (n = 57).MethodsOcclusal outcome was scored on dental casts at T1 (pre‐treatment), T2 (post‐treatment) and T3 (mean follow‐up 2.5 ± 0.9 years) using the weighted Peer Assessment Rating (PAR) Index. The paired sample t test and one‐way ANOVA followed by Tukey's post hoc test were used for statistical analysis.ResultsPAR was reduced by 95.7% and 89.9% at T2 and T3, respectively, compared with the start of treatment. The largest post‐treatment changes were found for overjet and buccal occlusion. Linear regression analysis did not reveal a clear effect (R‐Square 0.074) of age, sex, PAR score at T1, incremental PAR score T2‐T1, overjet and overbite at T1, and facial type on the changes after treatment (incremental PAR score T3‐T2).ConclusionsThe occlusal outcome achieved after Class II division 1 treatment with maxillary first permanent molar extractions was maintained to a large extent over a mean post‐treatment follow‐up of 2.5 years. Limited changes after treatment were found, for which no risk factors could be discerned.

Highlights

A great variety of treatment options exists for the treatment of Class II malocclusions, including facial orthopaedic, functional, non-extraction and extraction procedures
Recent alternatives for Class II correction by upper molar distalizing mechanics are provided by appliances fixed with temporary anchorage devices (TAD’s), an implant in the frontal part of the palate, or bone anchors attached to the zygomatic arches.[4]
Linear regression analysis for the effect of the independent variables age, sex, Peer Assessment Rating (PAR) score at T1, incremental PAR score T2-T1, overjet and overbite at T1, and facial type on the changes after treatment revealed only a minor effect of the change of the total PAR score during treatment on the changes after treatment (B = −0.291, 95% CI −5.581...−0.001, P = .049; R-Square .074)

Summary

| INTRODUCTION

A great variety of treatment options exists for the treatment of Class II malocclusions, including facial orthopaedic, functional, non-extraction and extraction procedures. As post-treatment changes occur mostly in the first 2 years,[12,13,14] the aim of this study was to evaluate occlusal results of Class II division 1 treatment with extraction of maxillary first permanent molars after a mean follow-up period of 2.5 years, in a large group of consecutively treated patients. Nomograms were used to visualize the degree of improvement following treatment and to visualize the degree of final improvement between the starting condition and 2 years post-treatment In these nomograms,[17] the degree of change of the weighted PAR score is divided into three categories: worse or no different (cases with less than 30% reduction), improved (patients with ≥30% reduction) and greatly improved (generally a reduction of 22 weighted PAR points or more).

| DISCUSSION

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Findings

| CONCLUSION